Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in CPP):

Solution:
#include<bits/stdc++.h>
using namespace std;
#define rep(i,n) for(int i=0;i<n;i++)
typedef long long ll;
int main(){
    int h,w,d[51][51],X[4]={1,0,-1,0},Y[4]={0,1,0,-1},c=0;
    cin>>h>>w;
    char s[51][51];
    rep(i,h)rep(j,w){
        cin>>s[i][j];
        if(s[i][j]=='.') c++;
    }
    rep(i,h)rep(j,w) d[i][j]=0;
    d[0][0]=1;
    queue<int> Qx,Qy;
    Qx.push(0),Qy.push(0);
    while(Qx.size()){
        int x=Qx.front(),y=Qy.front();
        Qx.pop(),Qy.pop();
        rep(i,4) if(s[x+X[i]][y+Y[i]]=='.'&&!d[x+X[i]][y+Y[i]]&&0<=x+X[i]&&x+X[i]<h&&0<=y+Y[i]&&y+Y[i]<w){
            d[x+X[i]][y+Y[i]]=d[x][y]+1;
            Qx.push(x+X[i]),Qy.push(y+Y[i]);
        }
    }
    if(!d[h-1][w-1]) cout<<-1;
    else cout<<c-d[h-1][w-1];
}